Comment by spwa4 | Hacker News Reader

Comment by spwa4 | Hacker News Reader

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Because as per usual it's silicon valley misunderstanding economics. AI is HPC. And how the HPC market worked before:

If you're the best performing "computing cluster" (ie. whatever you call the entity that can complete a massive calculation), you get a blank check from Congress.

Why? Because you need those calculations to "pump" nuclear weapons. They are needed to calculate both the geometry to make fusion bombs possible at all and to calculate the effect of a given geometry. They are the reason US/Russia/China have the biggest and strongest weapons known to humanity. And of course, they were replicated worldwide for this reason. I mean not that anyone will admit this but we don't have the best possible solution, and we don't know either the upper or lower limits for fusion devices (plus the lower limit would be very useful for energy generation, which for the US would effectively mean almost literally unlimited large marine ships that never need refueling. And yes, the solution to that problem is almost literally a 3d shape. Not just that, but mostly)

Now it appears it does not work the same when you democratize computation. Humans want a particular amount of computation and are willing to pay a given price for that. But the accountants still saw the blank check from before and ... do what accountants do. Economics don't change because you make things bigger and accessible, do they? Oh ... wait a second ...

As someone put it recently though, we now have data. 2.3% of humans in the US are willing to pay $20 per month for the support of a model like GPT-5.5/Claude code. If that's true (and after years of having this model, why wouldn't it be?) ... it means AI startups are doomed (because it's not even 10% of what they need it to be to make economic sense).

> Because you need those calculations to "pump" nuclear weapons. They are needed to calculate both the geometry to make fusion bombs possible at all and to calculate the effect of a given geometry. They are the reason US/Russia/China have the biggest and strongest weapons known to humanity.

We have a couple new nuclear weapon designs, but not really going for bigger or stronger. Just packaging.

We built the big powerful ones with 1960s computing.

Now, stockpile stewardship -- being sure that stuff will keep working without ongoing testing -- is a bit expensive in compute. You need early 2010s supercomputer power.

In other words, I strongly disagree that nuclear weapons are the primary driver of high-end compute.

High end compute also existed in the 60’s.

The military has already mastered fusion (power), and likely has mastered gravity in some form in secret. They aren’t using mainstream compute for these discoveries

> High end compute also existed in the 60’s.

Believe me, I know-- my dad did some work on the 360/44 and other large systems.

High end late 1960s compute -- of the sort used to go to the moon or to design big nuclear weapons -- was roughly 486DX4-100 class. Not individual computers; the total computing at DOE or NASA. Of course, it would be hard to replace either with a single 486 because of availability, usage at different geographic locations, etc.

You can assume a single large AMD Threadripper machine ($25k?) outclasses late-1960s DoE by roughly a factor of 50,000. And that assumes you didn't bother to put a GPU in it.

> The military has already mastered fusion (power), and likely has mastered gravity in some form in secret. They aren’t using mainstream compute for these discoveries

K

> We have a couple new nuclear weapon designs, but not really going for bigger or stronger. Just packaging.

There's many other considerations. Like the type and amount of fissile material. To name one that became well known: any plutonium needs to be refreshed (re-breeded I believe is the term) every few years.

Also, look at first designs: https://www.bbc.com/news/newsbeat-35242069 The weight is secret, but I think you can easily see it's going to be deep into "extremely impractical" territory.

Surely you can see why someone (especially aircraft designers) might ask for better versions. Ideally you'd like a version that fits on the hypersonic missiles and those things ... are just not going to work. The size. The shape. The weight. None of them will work.

Then a quick theoretical exploration will tell you that the minimum theoretical size of such a device is tiny. The scare was about "suitcase sized", but if you actually do the calculation looking for the minimum ... to do it however you need to create an explosion of the correct shape to get anywhere near those minimum sizes. And explosion simulations are a problem that utterly sucks ... Oh and these are secret military projects, these simulations, not very optimal. The people doing them are best described as loyal, and not as great physicists. Not saying they're terrible, but in the movie Oppenheimer you can clearly see why the best and brightest are not available for these things.

> There's many other considerations. Like the type and amount of fissile material. To name one that became well known: any plutonium needs to be refreshed (re-breeded I believe is the term) every few years.

Already mentioned in the comment you replied to:

> > Now, stockpile stewardship -- being sure that stuff will keep working without ongoing testing -- is a bit expensive in compute. You need early 2010s supercomputer power.

> Surely you can see why someone (especially aircraft designers) might ask for better versions. Ideally you'd like a version that fits on the hypersonic missiles and those things ... are just not going to work. The size. The shape. The weight. None of them will work.

The "new" US nuclear weapons are direct derivatives of older designs produced with less computing. B61-13 a direct child and similar footprint to 1967's B61. W87-1 direct descendent of the 80's W87. W93 is closest to a "clean sheet' design but hits similar size targets.

> Then a quick theoretical exploration will tell you that the minimum theoretical size of such a device is tiny. The scare was about "suitcase sized", but if you actually do the calculation looking for the minimum ... to do it however you need to create an explosion of the correct shape to get anywhere near those minimum sizes. And explosion simulations are a problem that utterly sucks ...

The backpack W54 was developed in 1959. Tinier devices were developed in the 60s and 70s but ultimately abandoned for proliferation rather than technical concerns. The total computing power used for this was miniscule.

Nuclear weapons are just not pushing forward supercomputing anymore. They did, for awhile, for stockpile stewardship, but we've become relatively confident that our stockpile will still work.

I disagree with some of the framing, but that's what good discussion is about -- figuring out where we agree and disagree.

But consumer uptake strikes me as the worst way to judge whether the big AI shops will make it. That's not where most of the leveraged user return or deployable capital is.

I'm sure Teller could make you a 10 gigaton nuke with a slide rule if you did not mind some sub scale tests.

Do you have a source for the 2.3%? I'd have thought it would be more. Does it include people who spend at least $20/mo, through a subscription or other means? Or what would that figure be? Also, we shouldn't forget about corporate customers.

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